This invention relates to an improved shipping container and, more particularly to an improved shipping container particularly adapted for the shipping of liquids in bulk.
In the transport of bulk materials in liquid form, such as in the shipping of liquid glues for industrial use, such materials are typically shipped in containers having side walls formed, for example, of corrugated cardboard. Because of the large outward forces imposed on the container by the bulk liquid, which is typically contained in a plastic bag in the container, considerable effort and expense has gone into attempts to contain these bulging forces. For example, in one commercially available design, the container is in the shape of a polygon which is strapped with metal reinforcing straps about its circumference. However, such solutions are not always successful and entail an added cost of the container.
In my U.S. Pat. No. 4,890,787, there is described an improved shipping container adapted particularly for transporting loads of material in pelletized, granular, powdered, or other particulate form. That container included an outer tube formed of four corrugated paperboard side walls and an inner tube which is formed in the shape of a cylinder open at both ends. The diameter of the inner cylinder is equal to the width of at least two of the side walls such that the cylinder extends generally to at least two of the side walls. The inner cylinder may be constructed out of laminated kraft paper of two or three plys and having a thickness from about 0.016 to 0.060 inch which is formed into the shape of an open-ended cylinder and glued to itself along an overlapping seam. The container is designed such that the material being shipped fills the interior of the inner cylinder and also the corner areas between the outer wall of the inner cylinder and the side walls. Still further the cylinder may be glued to two sides of the side wall such that in the knocked-down condition of the cylinder with the container flattened, the tube is likewise flattened. This permits the container to be stacked and shipped in a flat condition saving substantially on shipping space. However, when the container is erected, the inner tube immediately takes its cylindrical configuration.
It has now been found that the shipping container as described may be improved to make a shipping container particularly adapted for shipping of liquids in bulk with significantly increased resistance to outward bulging due to the weight of the liquid contained therein.